$3/$ A container has mercury

at $0C.$ A small hole of $1\mathrm{.}65m{m}^2$ allows $0\mathrm{.}126mg$ of

Hg to escape in $2\mathrm{.}25$ hours.

a$)$ Calculate the vapour pressure of Hg at$0C$

b$)$ use the equation of diffusion speed to show that

$\frac{dp}{dt}=-ap$

where p is the vapour pressure that escapes. How long does it take for the pressure to be $50\%$ of the original pressure.

if the volume of the container is${10}^{4}L?$